This invention relates to nibs for writing implements and more particularly, it concerns a writing nib structure and method of manufacture.
Commonly used felt tip pens and marking implements employ a nib by which ink or other marking fluid contained in a reservoir within the implement is fed by capillary action along the length of the nib to its projecting tip in contact with a writing surface. The popularity of such implements both as writing pens and as markers is perhaps attributable in substantial measure to such desirable characteristics as adaptability to a wide variety of writing surfaces, smoothness with which the pen tip or nib glides on a writing surface and continuity of ink or marking fluid flow through the nib onto a writing surface. A principal shortcoming of such felt tip pens and marking implements, however, is the deterioration with use of the writing nib tip to a degree that a clear line of uniform thickness becomes difficult to write, often before the supply of ink in the pen or implement is exhausted. As a result of this shortcoming, many materials and pen nib constructions have been developed out of efforts to achieve or retain the aforementioned desirable characteristics while at the same time strengthen or rigidify the pen nib to increase its useful life. Although much progress has been made in the development of stronger more rigid materials for writing pen nibs, the use of stronger nib materials involves a compromise between durability and writing smoothness. In other words, writing smoothness is increased with nib material softness whereas nib life is increased with harder and more rigid materials which have a tendency to scratch many writing surfaces.
An effective approach to the achievement of both strength and writing smoothness in a pen nib is exemplified by the disclosures of such U.S. Pat. Nos. as 3,094,736 issued June 25, 1963 to R. H. Bunzl et al, 3,167,803 issued Feb. 2, 1965 to Shigeki Shimamura, 3,213,025 issued Aug. 31, 1965 to C. Schreur and 3,464,775 issued Sept. 2, 1969 to K. F. Beal. The pen nib structures shown in these patents are generally characterized as having a relatively soft wicking core enclosed in a reinforcing sheath of relatively strong solid material. The nibs are usually formed by providing an elongated strand of the sheathed core element which is cut to the length of the individual nib and machined or otherwise treated on one end of the nib to leave the soft core projecting slightly from the corresponding end of the sheath as a writing tip.
Although the combination of nib strength and writing smoothness achievable by the aforementioned sheathed or reinforced nibs is highly desirable, the manufacturing costs associated with their manufacture in quantity are high principally because of the requirement for forming a writing tip on each individual nib. While such costs may fall within tolerable limits where the writing tip end of each nib is a surface of revolution, such as conical or hemispherical, they are increased to unjustified levels for non-circular nibs of the type used, for example, in wide-line writers or marking implement nibs.